Traveling wave tubes



March 26, 1957 R. WARNECKE ErAL 2,786,959

TRAVELING WAVE TUBES Filed Nov. 25, 1953 4 Sheets-Sheet 1 [JV/IA 4 1a /7 J 26' 8 .9 I

1 4L W WW/pf 7/ I5 March 26, 1957 WARNECKE ET AL TRAVELING WAVE TUBES 4 Sheets-Sheet 2 Filed Nov. 25, 1953 0 a. 7 J a a March 1957 R. WARNECKE ETAL TRAVELING WAVE TUBES 4 Sheets-Sheet 8 Filed Nov. 25, 1953 March 26, 1957 R. WARNECKE ETAL 2,7

TRAVELING WAVE TUBES Filed Nov. 25, 1953 4 Sheets-Sheet 4 J 2 F b o, 9 I HM HI Film a .m .5.inmfii\ wm 4 a A a m o 0 W a nited States TRAVELING WAVE TUBES Robert Warnecke and Harry Huber, Paris, France, as-

signors to Compagnie Generale de Telegraphic Sans Fil, a corporation of France The present invention relates to traveling wave tubes of the amplifier or oscillator type having crossed magnet c and electric fields and a circular interaction space. It is known that in this type of tubes there is produced an interaction between an electromagnetic wave which is propagated along a delay line and an electron beam which propagates in the electric field of this wave and is subject to the action of a magnetic field and of a D. C. electric field, these two fields being perpendicular to each other and to the electron beam and being constant in time. An amplifier tube of this type has been described in the American Patent No. 2,511,407 issued to W. Kleen et al. and in an article published in the Pro. Inst. Radio Engineers, May 1950, page 480.

Further, an oscillator tube of this type has been described in the copending patent application No. 281,347 in the U. S. A. filed April 9, 1952, for Improvements in Traveling Wave Oscillators, and in an article published in the Comptes Rendus de lAcademies des Sciences, volume 235, pages 236-238, where it was referred to under the name of Carcinotron tube, Carcinotron being a registered trademark.

Certain difiiculties arise in constructing this kind of tube and the present invention has for its object to obviate these difiiculties. These difiiculties concern, among others, the disposition of the delay line, the centering of the negative electrode and the matching of the delay line to the input and output conductors.

in particular, it is necessary that the space between the delay line and the negative electrode be as uniform in width as possible. For example, if this space is of the order of 3 mm., the irregularities must not exceed Furthermore, once the tube is assembled it must be possible to match the delay line to the antenna or antennas.

The invention will be better understood from the accompanying drawings given merely by way of example and in which:

Fig. 1 shows a sectional view of an amplifier tube of cylindrical type according to the invention;

Fig. 2 shows the same tube in section along line AB of Fig. 1;

Fig. 3 shows the delay line utilized in the tube of Fig. 1 developed out to show the interdigitated fingers;

Fig. 4 shows a detail of the tube of Fig. 1;

Figs. 5 and 6 show two embodiments of the cooling means for the tube;

Figs. 7 to 10 show sectional views of modifications of the tube of Figs. 1 and 2;

Fig. 11 shows a sectional view of an oscillator according to the invention of the same structural form as the amplifier of Fig. 1;

Fig. 12 shows diagrammatically another oscillator of the same type;

Fig. 13 shows very diagrammatically another amplifier according to the invention which is similar to that of Fig. 1; 7

Figs. 14 and 15 show sectional views of two other embodiments of tube of toroid type.

tent

The embodiment shown in Figs. 1 to 3 relates to the above-mentioned traveling wave amplifier.

An amplifier of this kind comprises, as is known:

a. A delay line 1, for example of the interdigital type, which is provided with an attenuated zone 2 and is well matched in the frequency band of the tube.

b. A negative electrode 3 which defines with the delay line the interaction space.

0. An electron optical system 4 adapted to produce an electron beam and comprising a cathode 5 and a positive focussing electrode 6.

d. An electron collector 7 rigidly connected to the envelope 8 of the tube.

a. An uncoupling screen 9 disposed between the be ginning and the end of the delay line.

Conductors 10 for applying the voltage to the electrodes and which are housed in an appendix 11.

g. An input antenna 12.

11. An output antenna 13.

The tube of Fig. l is cylindrical in shape. The tubes of the toroid shape will be examined hereinafter.

As has been hereinbefore mentioned, the tubes of the type considered are placed in a magnetic field directed along the axis of the tube. In the case of the tube of Fig. i, this field is created by a magnet diagrammatically shown at M (Fig. 2).

In the tube according to the invention, the envelope 8, which is machined out of a copper block, comprises on its inner wall annular recesses 15 and 16. Two circular rings 17 and 18, which form an interdigital delay line, are rigidly mounted, for example by screws or by brazing, on the shoulders formed by the recesses 15 and 16. The two rings include fingers 19 so that each one of them forms a comb, the two combs thus forming an interdigital delay line 1.

The rings 17 and 18, as well as the fingers 19, are machined from a block of copper or another non-magnetic metal which is more rigid, for example molybdenum.

On the ring 18 is attached a side member 20 which is covered by a cover 21. in the side member 20 is fixed a journal 22 which is disposed along the axis of the envelope 8. On this journal is freely mounted a sleeve 23 whose two ends are integral with two discs 24 and 25. In these two discs are mounted three insulators 26, for example of quartz. These insulators support the negative electrode 3, as shown in the drawing. The uncoupling screen 9 and the cathode 5 are fixed to the negative electrode 3.

Those fingers 19 of the delay line 1 which are nearest respectively to the antennas 12 and 13 each comprise a tongue 27 which is used for matching the delay line 1 to the corresponding antenna. This tongue 27 is fixed to the appropriate finger 19 for example by rivets, and, preferably, the length of the tongue 27 is equal to one half of the length of the wave corresponding to the mean frequency of the band of frequencies for which the tube is designed.

The above-described assembly has many advantages. As can be seen in the drawing, the envelope 8, the delay line 1, the collector 7 and the plate 6 constitute a first assembly or unit, which is in the form of a perfectly rigid block. Furthermore, the negative electrode 3, which is mounted on the journal 22 constitutes, with the various elements it supports, a second assembly or unit also in the form of a rigid block. The centering of this second assembly inside the first assembly is moreover very easy and the space between the negative electrode 3 and the delay line 1 may be very accurately set and remains perfectly constant. I

Another advantage of the assembly according to the invention is the fact that the negative electrode 3 is ca- 3 v I prable of being rotated on the journal 22. This facilitates the matching of the tube to the antennas 12 and 13';

To effect this matching of the tube, the tongue 27 is deformed, until there is obtained a suitable matching for the whole operational range of the tube. In order to allow access for a tool to deform to the tongue 27, 1e negative electrode 3 as shown in Fig. l is rotated clockwise or anticlockwise about the journal 22 so as to leave a clear radial path toward the end fingers of the delay line 1. Once the tube has. been matched to the antennas, the negative electrode 3 is brought back in position and is locked in any suitable manner, for example by a nut 28. Then the collector 7, the side member 29 and the cover 36 are placed in position. When the tube is closed, the air contained therein is evacuated through the exhaust appendix 14.

The particular structure of the tube aids, furthermore, the dispersion of heat owing to the close contact between the. various elements which form a single unit with the envelope 3. jacket 31 (Figs. 5 and 6) having an inlet 32' and an outlet 33. The inlet is positioned in front of the collector 7.

In the embodiment shown in Fig. l the double wall 31, which is represented in Fig. 5, comprises a brass "or copper band which is provided at each end with two The latter also comprises a double water rolled or formed-over portions 34 and which are firmly drawn together by means of screws 36 and a coupling block 38. The water jacket is rendered watertight by a seal or gasket, for example of asbestos impregnated with tar, colloidal graphite or varnish.

The water jacket may also be welded to the envelope of the tube. A jacket of this kind is shown in Fig. 6.

Fig. 11 shows an oscillator which is identical in structure to the amplifier of Fig. 1, except that instead of an input antenna 12 and an output antenna 13 there is a single output antenna 13a. Furthermore, the attenuated portion 2a is placed at the end opposite to that at which this antenna is located, as described in the co-pending application mentioned above.

It is clear that many modifications may be made to the described structure. Thus the delay line may be of another type.

Fig. 13 very diagrammatically shows an amplifier similar to that shown in Fig. 1. It differs from the amplifier of Fig. 1 in that the antennas 12 and 13 are disposed tangentially to the envelope 8.

Some modifications of the tube according to the invention have been shown in Figs. 7 to 13.

Fig. 7 shows an assembly which is identical to that shown in Figs. 1 and 2 except that the pins 39, on which are mounted the insulators 26 that support the negative electrode 3, are integral with the side member 2% The assembly comprising the side member 2%) and the negative electrode 3, which it supports through the medium of the pins 39 and the insulators 26, may therefore pivot inside the envelope 8 on the shoulder 26. Once the final matching of the tube has been accomplished as described above, the side member 29 is placed in position and locked, firstly to the ring 17 by screws and, secondly, to the pins 39 and the central pin 41 which is integral with the side member 20. The covers 21 and 39 are then placed in position.

In the modification shown in Fig. 8, the side members 28 and 29 have been eliminated and the insulators are mounted directly on the covers 21 and 3! Except for this detail, the assembly is identical to that shown in Fig. 7.

In the modification shown in Fig. 9, which is otherwise identical to that shown in Fig. 7, a single insulator 62 has been interposed between the journal 22 and the negative electrode 3 to support the latter.

Fig. 10 shows another modification of the tube according to the invention. This modification is very' similar to that shown in Fig. 2. However, the side member 4 29 is eliminated and the journal is cut short and does not reach the covet-'30; When the matching of the tube has been accomplished, the'negative electrode 3 is locked in position by nuts 42 and 43. Further, the ring 18 is fixed directly on the side member 21.

The principal difference between the modifications shown in Figs. 2 and ll)= consists in the cooling means used. The exterior water jacket is replaced by the following means. Water is injected in the tube at 44 and passes through a passageway 45- provided in the journal 22 and a spiral passageway provided in the cover 21, and then flows out of the tube at 46.

Fig. 12 shows, as a still further modification, an oscillator according to the invention. In this embodiment the envelope of the tube comprises a cup 47' and a base 33. The pin 22 is here replaced bya relatively massive block t). One half, 18, of the delay line is embedded in the base 48 and the other half, 17, is embedded in the block 49. The negative electrode 3, also in the form of a cup, is rotatively mounted on the block 44 through a sleeve 50 and is locked in position after the matching of the tube by a screw 51.

It will be noticed that the antenna 139. and the foot 10' are disposed along the axis of the tube and extend through polar elements 52 and 53 which are provided with apertures for this purpose.

Figs. 14 and 15 show two other embodiments of the tube according to the invention. The latter relate to tubes of the toroid type, the magnet 54 being housed inside a central hole provided in' the tube. These tubes are in other respects substantially identical to the tubes shown respectively in Fig. 2 and 9. The only difference is that the journal 22 is replaced by the magnet 54. In the case of Fig. 15, the covers 55 and 56 are of magnetic materials.

tn the case of Fig. 14, polar pieces 57 and 58 are provided and these pieces cover the side members 59 and 60 of the tube respectively.

What we claim is:

1. In a travelling wave electron discharge tube of the kind comprising a substantially cylindrical envelope and,

within said envelope, a first electrode in the form of a circular delay line, a second electrode defining an interaction space between said first and second electrodes, a cathode, a focussing electrode, a collector, coupling and matching means at least at one end of said delay line and uncoupling means distinct from said collector between the ends of said delay line, the structure comprising a first block including said envelope having said delay line, coupling means, collector and focussing electrode rigidly connected to said envelope, a second block including said second electrode having said cathode and uncoupling means rigidly connected to said second electrode, means coaxially mounting said second block within said first block for rotation relatively thereto, means electrically insulating said blocks from each other, andreleasablc means rigidly fastening said blocks against relative rota tion.

2. A travelling wave tube according to claim 1 wherein said coupling means are located tangentially to said envelope.

3. A travelling wave tube according to claim 1 wherein said coupling means are located axially with respect to said envelope.

4. In a'travelling wave electron discharge tube type of the kind comprising a substantially cylindrical envelope and, within said envelope, a first electrode in the form of a circular delay line, a second electrode defining an interaction space between said first and second electrodes, a cathode, a focussing electrode, a collector, coupling and matching means at least at one end of said delay line and uncoupling means distinct from said collector between the ends of said delay line, the structure comprising a first block including said envelope having said delay line, coupling means, collector; and focussing electrode rigidly connected to said envelope, at second block including said second electrode having said cathode and uncoupling means rigidly connected to said second electrode, one of said blocks comprising a pin rigidly connected thereto and coaxial with said envelope, the other block being rotatably mounted on said pin, means insulating said releasable block from said pin and other means fastening said other block on said pin in a selected position against rotation.

5. A travelling wave tube according to claim 4 wherein said first block comprises a bottom plate secured thereto, said pin being secured to said bottom plate, said other block comprising two plates in spaced relationship rotatably supported on said pin and insulating means supporting said second electrode between said two plates.

6. A travelling wave according to claim 4 wherein said pin has a free end and supports thereon said second block.

7. A travelling wave tube according to claim 4, wherein cooling means are provided within said pin.

8. A travelling wave tube according to claim 4 wherein said pin is constituted by a magnet.

9. A travelling wave tube according to claim 8 wherein the end walls of said cylindrical envelope are made in a magnetic material.

10. A travelling wave tube according to claim 1 wherein said second block comprises a pin insulated from said second electrode and coaxial with said envelope; an end plate supporting said pin, a second end plate supporting said first end plate and forming an end Wall of said envelope, said first end plate being freely rotatable upon said second end plate and means for fixedly positioning said first plate within said first block.

11. A travelling wave tube according to claim 1 wherein said second electrode is in the form of a cup partly surrounding said delay line.

12. In a travelling wave electron discharge tube of the kind comprising a substantially cylindrical envelope and, within said envelope, a first electrode in the form of a circular delay line, a second electrode defining an interaction space between said first and second electrodes, a cathode, a focussing electrode, a collector, coupling and matching means at least at one end of said delay line and uncoupling means distinct from said collector between the ends of said delay line, the structure comprising a first block including said envelope having said coupling means, collector and focussing electrode rigidly connected to said envelope, said delay line being an interdigital delay line constituted by two similar parts having respectively a circular body and interdigitated fingers, said envelope having two peripheral internal end shoulders, said bodies being respectively located in said shoulders, a second block including said second electrode having said cathode and uncoupling means rigidly connected to said second electrode, said envelope comprising two end plates respectively located in said shoulders, a pin fastened in one of said plates coaxially with the envelope, and means rotatably supporting said second block on said pin and insulating the same therefrom.

13. A travelling wave tube according to claim 12 Wherein at least the finger of said delay line which is the nearest to said coupling means is longer than all the other fingers.

14. A travelling wave tube according to claim 12 wherein at least the finger of said delay line which is the nearest to said coupling means is longer than all the other fingers by half the wavelength corresponding to the mean frequency of the frequency band of said tube.

l5. A travelling wave tube according to claim 12 wherein at least the finger of said delay line which is the nearest to said coupling means is longer than all the other fingers, a deformable element being connected to said finger within said envelope whereby matching may be achieved by deformation of said element.

Lerbs Aug. 28, 1951 Willshaw Jan. 8, 1952 

